The AfLinks plugin for WordPress inserts affiliate links into the WordPress content, i.e. ads are attached to certain keywords in the WP entry. Hovering such a link with the mouse will show a little popup with an image and a description of the advertised article. The links are generated either automatically by the plugin, or the author can select products via a search interface from a popup which will be available in the WP admin, and set links on keywords manually.
The affiliate data are imported from the respective webmaster's account at Affili.net. The import works semi-automatically via an importer script, it can also be fully automatized with a cronjob.
With this plugin, webmasters have an additional possibility to monetize their blogs. It also is a good way to circumvent "banner-blindness" and ad blockers. ;-) The automatic feature is especially interesting for large archives, while the manual feature is great for high quality advertising in the content.
Note: This plugin is only available in German, and only for the Germal Affili.net at the moment. If International webmasters and webmasters working with other affiliate networks are interested in this plugin, please let me know, and I will create an English version, and I might also extend the plugin for other networks.